Aminoacyl-tRNA synthetases (ARSs) play a key role in one of the most important cellular processes, namely protein biosynthesis. They catalyze the covalent attachment of amino acids to their cognate transfer RNAs (tRNAs), an essential step in the translation of the genetic code. ARSs are multi-domain proteins, with domains that have distinct roles in aminoacylation of tRNA and maintaining high accuracy in protein synthesis. These domains carry out their specific functions in a highly coordinated manner. The coordination of their function, therefore, requires domain-domain communication. Various biochemical and structural studies provide evidence to suggest that domain-domain communication clearly exists in ARSs. In general, communication between distantly located domains in multi-domain proteins is believed to be propagated through networks of coupled motions of structural elements. However, for ARSs, the molecular mechanism of signal propagation from one domain to another domain remains poorly understood. This proposal aims to explore the molecular basis of domain-domain communication in two different classes of ARSs. In particular, we will examine the role of evolutionarily coupled networks of residues in facilitating domain dynamics, thereby maintaining the fidelity of protein biosynthesis. Given the multidisciplinary nature of the problem, our study will employ both computational and experimental methods. The principal investigator and a research team of four undergraduate students will carry out a number of computational studies involving bioinformatics, statistical coupling analysis, and simulations (normal mode and molecular dynamics) to gain insight into the evolution-structure-dynamics relationships in ARSs. Complementary mutagenesis studies of specific residues will be conducted and their role in enzyme function will be evaluated. These experimental studies will provide further details of the communication pathway. Understanding domain-domain communication of ARSs at the molecular level has significant implications for drug design. The essential role of ARSs in protein synthesis has made them potential drug targets. The identification of allosteric residues at a non-catalytic site can be exploited to develop a new generation of therapeutics targeted against pathogenic ARSs. Results of our studies can be used in the design of small molecules targeting distant sites that are energetically coupled to the aminoacylation and/or the editing active site(s). PUBLIC HEALTH RELEVANCE: Statement Understanding domain-domain communication of ARSs at the molecular level has significant implications for drug design. The essential role of ARSs in protein synthesis has made them potential drug targets. Results of our studies can be used in the design of small molecules targeting distant sites that are energetically coupled to the aminoacylation and/or the editing active site(s). [unreadable] [unreadable] [unreadable]